Remove QuadCuller class and make QuadSink concrete

cc/BUILD.gn

Index: cc/BUILD.gn
diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index fef36f1eb1fb710bc1b0f7bcc172147b20229777..05d6f5cd93e4cee1b4a6efad6d0643f036c18bb7 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn
@@ -165,6 +165,7 @@ component("cc") {
     "layers/picture_layer_impl.cc",
     "layers/picture_layer_impl.h",
     "layers/quad_sink.h",
+    "layers/quad_sink.cc",
     "layers/render_pass_sink.h",
     "layers/render_surface.cc",
     "layers/render_surface.h",
@@ -430,8 +431,6 @@ component("cc") {
     "trees/proxy.h",
     "trees/proxy_timing_history.cc",
     "trees/proxy_timing_history.h",
-    "trees/quad_culler.cc",
-    "trees/quad_culler.h",
     "trees/single_thread_proxy.cc",
     "trees/single_thread_proxy.h",
     "trees/thread_proxy.cc",
@@ -562,6 +561,7 @@ source_set("test_support") {
     "test/layer_tree_pixel_test.h",
     "test/layer_tree_test.cc",
     "test/layer_tree_test.h",
+    "test/mock_occlusion_tracker.h",
     "test/mock_quad_culler.cc",
     "test/mock_quad_culler.h",
     "test/ordered_texture_map.cc",